The present invention relates to data processing apparatuses and data recording media and, more particularly, to a process of embedding a watermark (information to be embedded) in digital data such as audio data obtained by electronic distribution or from recording media, by using a specific watermarking method such as a watermarking method employed for versatile data reproduction apparatuses.
In recent years, with the progress of digitization of video data and audio data, the facility of forming a perfect copy of original digital data has become a great problem.
As a countermeasure against such problem, a watermarking technique has been employed. The watermarking technique is described in detail in Japanese Published Patent Applications Nos. Hei.9-191394 and Hei.9-191395.
The watermarking technique is not a direct method for preventing original digital data to be reproduced, such as video data or audio data, from being copied, but a method for restricting copying of the original digital data by embedding copyright information relating to the copyright for the digital data, in the digital data.
For example, by embedding, as a watermark, copyright information indicating the name of the copyright holder (information source) in digital data such as video data and audio data, the copyright information (watermark) is copied when the digital data is copied. Therefore, when the copyright holder has found digital data (video data or audio data) formed by illegal copying, the copyright holder can prove the illegality by using the copyright information embedded in the digital data.
Hereinafter, the watermarking technique will be described with reference to FIG. 18.
FIGS. 18(a) and 18(b) are diagrams for explaining, as an example of a watermarking technique for video, a process of embedding information relating to the copyright holder of digital video data (relevant information Dwmi) in digital video data to be supplied from the distribution end to the user (supply digital data). Hereinafter, this relevant information is called xe2x80x9cwatermarkxe2x80x9d or xe2x80x9cembedded informationxe2x80x9d.
To simplify the description, as shown in FIG. 18(a), it is assumed that an image F is a gray-scale still picture, and its size is vertical 50 pixelsxc3x97horizontal 50 pixels. Further, each of pixels P constituting the image F takes an integral value within a range from 0 to 99, as a luminance level (pixel value) indicating its brightness.
In the watermark embedding process, initially, the image F is divided into a plurality of blocks B each comprising a predetermined number of pixels (vertical 10 pixelsxc3x97horizontal 10 pixels). That is, the original still picture F is divided into 25 blocks (vertical 5 blocksxc3x97horizontal 5 blocks) as shown in FIG. 18(b). At this time, the pixel values constituting image data corresponding to each block (sub-imaqe) B are represented as the values of the respective components of a matrix of 10 rowsxc3x9710 columns.
Next, this matrix is subjected to DCT (Discrete Cosine Transform) to obtain a transformed matrix of 10 rowsxc3x9710 columns. The numerical values arranged at the lower-right portion of the transformed matrix are values which represent the high-frequency components of the image data corresponding to the original image.
By the way, it is known that the human sense of sight is less responsive to change of high-frequency components of image data than to change of low-frequency components thereof. In other words, even if the original image is subjected to image processing for changing the values of the high-frequency components to slightly different values, it is very difficult for the human sense of sight to recognize the difference between the processed image (reconstructed image) and the original image. The reconstructed image is, to be specific, an image corresponding to image data reconstructed from an inversely-transformed matrix which is obtained by subjecting the transformed matrix to inverse DCT.
The watermarking technique for video utilizes the above-described characteristics of human sight, and it is able to embed information in the image data corresponding to the original image, by controlling the high-frequency components of the original image, without making the viewer sense the degradation of the image quality.
Although the watermarking technique for video has been described above, there is a watermarking technique for audio. Further, there is a watermarking technique which is able to extract or remove information from video data or audio data in which the information is embedded.
Moreover, according to the watermarking technique, when digital data recorded in a digital recording medium is copied to another digital recording medium, information embedded in the digital data can be copied as well. Further, when the digital data recorded in the digital recording medium is once converted to analog data by a DA converter and then recorded in an analog recording medium, the embedded information can be held in the analog data recorded in the analog recording medium.
Hereinafter, a description will be given of the watermarking technique for audio.
FIG. 19 is a diagram conceptually illustrating an information embedding process and an information extracting process for digital audio data.
With reference to FIG. 19, signature data (information to be embedded) is embedded in digital audio data recorded as an audio data file ODau (signature data embedding process Pad), and then the digital audio data in which the signature data is embedded is recorded as a signature-data-embedded audio data file SDau.
The signature data Dwmx embedded in the digital audio data is extracted in accordance with the digital audio data which is recorded as the audio data file ODau and the digital audio data which is recorded as the signature-data-embedded audio data file SDau (signature data extraction process Pex).
FIG. 20 is a flowchart of the information embedding process.
Initially, digital audio data is subjected to blocking (step S1). This process is to divide the digital audio data into a plurality of data groups (blocks) each comprising a predetermined number of sampling data, for convenience in the subsequent process.
Next, each block is subjected to the Fourier transform (step S2). The arithmetic operation for the Fourier transform will be later described in detail.
Thereafter, the following data transform is carried out as the watermark (information to be embedded) embedding process.
The watermark is composed of multiple bits of digital data (signature data), and each bit of the signature data corresponds to each block.
Initially, it is confirmed that the value of each bit as a component of a block string (bit string) of the signature data is xe2x80x9c0xe2x80x9d or xe2x80x9c1xe2x80x9d (step S3). A block corresponding to a bit of xe2x80x9c0xe2x80x9d is not subjected to the watermark embedding process. A block corresponding to a bit of xe2x80x9c1xe2x80x9d is subjected to the watermark embedding process, wherein an imaginary part and a real part of a function which has been obtained by subjecting the audio data corresponding to this block to the Fourier transform (hereinafter, referred to as a Fourier transformed function), are replaced with each other, and the real part is multiplied with xe2x88x921 (step S4). This process is performed for each block.
Then, the Fourier transformed function corresponding to each block is subjected to the inverse Fourier transform (step S5). Thereby, audio data of each block is restored. The inverse Fourier transform will be later described in more detail.
Through the above-described processes, information to which a normal human ear does not respond is embedded in the audio data.
Hereinafter, the respective processes of the watermarking technique will be described in more detail.
Initially, the Fourier transform and the inverse Fourier transform will be briefly described. The Fourier transform employed in the process of embedding a watermark (information to be embedded) is called xe2x80x9cdiscrete Fourier transformxe2x80x9d which is defined as follows.
When a discrete one-dimensional real number function f(n) (nxcex5z, 0xe2x89xa6n less than N) is given, a function obtained by performing the discrete Fourier transform on the f(n) is defined by a discrete one-dimensional complex number function F(k) (kxcex5z, 0xe2x89xa6k less than N) which is given by formula (1).
Here, Z denotes the set of whole integers. Further, formula (1) satisfies the conditions given by formulae (2) and (3).                               F          ⁢                      xe2x80x83                    ⁢                      (            k            )                          =                              ∑                          n              =              0                                      N              -              1                                ⁢                      xe2x80x83                    ⁢                      f            ⁢                          xe2x80x83                        ⁢                          (              n              )                        ⁢                          xe2x80x83                        ⁢                          W              N                              -                lai                                      ⁢                          xe2x80x83                        ⁢                          (                                                k                  =                  0                                ,                                                      1                    ⁢                    …                    ⁢                                          xe2x80x83                                        ⁢                    N                                    -                  1                                            )                                                          (        1        )            xe2x80x83j2=xe2x88x921xe2x80x83xe2x80x83(2)
WN=ej2xcfx80/N=cos(2xcfx80/N)+j sin(2xcfx80/N)xe2x80x83xe2x80x83(3)
Further, the inverse discrete Fourier transform will be described hereinafter.
When a discrete one-dimensional real number function f(n) (nxcex5z, 0xe2x89xa6n less than N) is given and a discrete one-dimensional complex number function F(k) (kxcex5z, 0xe2x89xa6k less than N) is a function obtained by performing the discrete Fourier transform on the f(n), the following formula (4) holds.
Here, Z denotes the set of whole integers. Further, formula (4) satisfies the conditions given by formulae (5) and (6).                               f          ⁢                      xe2x80x83                    ⁢                      (            n            )                          =                              ∑                          n              =              0                                      N              -              1                                ⁢                      xe2x80x83                    ⁢                      F            ⁢                          xe2x80x83                        ⁢                          (              n              )                        ⁢                          xe2x80x83                        ⁢                          W              N              lai                        ⁢                          xe2x80x83                        ⁢                          (                                                k                  =                  0                                ,                                                      1                    ⁢                    …                    ⁢                                          xe2x80x83                                        ⁢                    N                                    -                  1                                            )                                                          (        4        )            xe2x80x83j2=xe2x88x921xe2x80x83xe2x80x83(5)
WN=ej2xcfx80/N=cos(2xcfx80/N)+j sin(2xcfx80/N)xe2x80x83xe2x80x83(6)
Next, the watermark embedding process for audio data will be described more specifically.
First of all, blocking of audio data will be described with reference to FIG. 21.
Blocking is a process to represent sample values Sound(i) of digital audio data in which a watermark is to be embedded (hereinafter, referred to as target audio data) as a set of blocks each comprising samples as many as the n-th power of 2 (2n). Here, it is assumed that the total number of blocks obtained by blocking the target audio data is (t+1), the first block is block B0, the k-th block (k: arbitrary number) is block Bk, and the last block is block Bt. Further, the sample values of the k-th block are represented by Bk(j).
The relationship between the sample values Sound(i) of the target audio data and the respective sample values Bk(j) in the block is represented by the following formula (7).
Bk(j)=Sound(i)
where Z denotes the set of whole integers, k and j satisfy k,jxcex5Z, and i satisfies i=2nk+j(0xe2x89xa6j less than 2n).
It is needless to say that the variables n and k used here are different from the variables n and k used in formula (1) which defines the general discrete one-dimensional Fourier transform and formula (4) which defines the discrete one-dimensional inverse Fourier transform.
Next, the watermark embedding process will be described.
Initially, the audio data (sample values) Bk(j) of the k-th block Bk are subjected to the discrete Fourier transform to obtain data Fk(m). Here, k is a variable indicating an arbitrary block amongst the blocks B0xcx9cBt, and it satisfies kxcex5z, kxcex5[0,t(total block number)].
Further, a data bit string to be inserted is defined by a one-dimensional discrete integral number function U(d), and data which is obtained by embedding information in the data Fk(m)(mxcex5z,mxcex5[1,2n]) according to the value of each bit in the data bit string defined by the function U(d), is represented by Fxe2x80x2k(m).
Here, d and dn satisfy the condition (d,dnxcex5z). When dn satisfies dn less than 2nxe2x88x921, U(d) is 1 or 0. When d does not satisfy dxcex5[1,dn]), U(d) is 0.
Then, Fxe2x80x2k(m) is represented by the following formulae (8)xcx9c(15), wherein m satisfies mxcex5z, mxcex5[1,2n].
Re(Fxe2x80x2k(m))=xe2x88x92Im(Fk(m))(when U(m)=1)xe2x80x83xe2x80x83(8)
Re(Fxe2x80x2k(m))=Re(Fk(m))(when U(m)=0)xe2x80x83xe2x80x83(9)
Im(Fxe2x80x2k(m))=Re(Fk(m))(when U(m)=1)xe2x80x83xe2x80x83(10)
Im(Fxe2x80x2k(m))=Im(Fxe2x80x2k(m))(when U(m)=0)xe2x80x83xe2x80x83(11)
Re(Fxe2x80x2k(2xe2x80x3xe2x88x92m+1))=xe2x88x92Im(Fk(m))(when U(m)=1)xe2x80x83xe2x80x83(12)
Re(Fxe2x80x2k(2xe2x80x3xe2x88x92m+1))=Re(Fk(m))(when U(m)=0)xe2x80x83xe2x80x83(13)
Im(Fxe2x80x2k(2xe2x80x3xe2x88x92m+1))=Rc(Fk(m))(when U(m)=1)xe2x80x83xe2x80x83(14)
Im(Fxe2x80x2kxe2x88x92(2xe2x80x3xe2x88x92m+1))=Im(Fk(m))(when U(m)=0)xe2x80x83xe2x80x83(15)
The above-described formulae (8)xcx9c(11) are applied to the low-frequency components amongst the 2n pieces of data (frequency components) Fk(m) obtained by subjecting the 2n pieces of data (sample values) Bk(j) to the discrete Fourier transform. On the other hand, the above-described formulae (12)xcx9c(15) are applied to the high-frequency components of the 2n pieces of data (frequency components) Fk(m) obtained by subjecting the 2n pieces of data (sample values) Bk(j) to the discrete Fourier transform.
Further, as represented by formulae (9), (11), (13) and (15), a block corresponding to a bit of 0 in the signature data bit string is not subjected to the watermark embedding process. On the other hand, as represented by formulae (8), (10), (12) and (14), a block corresponding to a bit of 1 in the signature data bit string is subjected to the watermark embedding process, in which the imaginary part and the real part of the data Fk(m) obtained by the Fourier transform of the audio data (sample values) Bk(j) corresponding to this block are replaced with each other, and the real part is multiplied with xe2x88x921.
Further, the watermark embedding process is performed on pairs of the Fourier transformed data on the low-frequency side and the corresponding Fourier transformed data on the high-frequency side so that the target audio data in which information is embedded is not offensive to the ear of the listener. Here, the m-th Fourier transformed data Fxe2x80x2k(m) which has been subjected to the watermark embedding process corresponds to the (2nxe2x88x92m+1)th Fourier transformed data Fxe2x80x2k(2nxe2x88x92m+1) which has been subjected to the watermark embedding process.
Next, the watermark extraction process will be described.
FIG. 22 is a flowchart of the watermark extraction process.
Initially, audio data which has been subjected to the information embedding process is divided into plural blocks (step S11a), and each block is subjected to the Fourier transform (step S12a). Further, audio data which has not been subjected to the information embedding process is divided into plural blocks (step S11b), and the audio data of each block is subjected to the Fourier transform (step S12b).
Then, the data obtained as the results of the above-described Fourier transform steps are compared, block by block, between the blocks of the audio data which has been subjected to the information embedding process and the corresponding blocks of the audio data which has not been subjected to the information embedding process (step S13).
As the result of the comparison, when the data of the corresponding blocks agree with each other, it is decided that no information is embedded in the block which has been subjected to the information embedding process, and the signature data bit is 0 (step S14). When the data of the corresponding blocks are different from each other, it is decided that information is embedded in the block which has been subjected to the information embedding process, and the signature data bit is 1 (step S15).
This process is repeated block by block to extract the bit string (embedded information) constituting the signature data.
Next, the watermark (information to be embedded) embedding process and the watermark (embedded information) extracting process will be described more specifically.
Initially, the process of embedding information in each block will be described.
In the following description, Sound(n) represents audio data (sample values) in one block in which signature data is to be embedded, and syomei[u] represents a signature data bit string to be embedded in data which is obtained by subjecting the audio data Sound(n) in one block to the Fourier transform. Further, F[Sound](p) represents data obtained by subjecting the target audio data Sound(n) to the discrete Fourier transform, and F[Sound](p) represents data obtained by embedding the signature data bit string in the F[Sound](p).
Here, the audio data Sound(n) is a function defined in the integral space and having an integer as its value, and n=0,1, . . . ,N.
Further, the signature data bit string syomei[u] is also a function defined in the integral space (refer to formula (16)) and having only 0 or 1 as its value, and u=0,1.
syomei[u]={1,0}xe2x80x83xe2x80x83(16)
When the audio data Sound(n) is subjected to the Fourier transform, the corresponding Fourier transformed data F[Sound](p) is obtained as follows.                                           F            ⁡                          [              Sound              ]                                ⁢                      xe2x80x83                    ⁢                      (            p            )                          =                              ∑                          n              =              0                        N                    ⁢                      xe2x80x83                    ⁢                      Sound            ⁢                          xe2x80x83                        ⁢                          (              n              )                        ⁢                          xe2x80x83                        ⁢                          ⅇ                              j                ⁢                                  xe2x80x83                                ⁢                2                ⁢                                  xe2x80x83                                ⁢                π                ⁢                                  xe2x80x83                                ⁢                pn                ⁢                                  /                                ⁢                N                                                                        (        17        )            
This F[Sound](p) is a function defined in the integral space and having a complex number as its value, and p=0,1, . . . N.
Assuming that the real part of the Fourier transformed data F[Sound](p) which is a complex number is Re{F[Sound](p)} while the imaginary part thereof is Im{F[Sound](p)}, the data Fxe2x80x2[Sound](p) can be represented by using the above-described formulae (8)xcx9c(15) in accordance with the value of the signature data bit string syomei[u].
Assuming that the signature data bit string to be embedded in the Fourier transformed data F[Sound](p) corresponding to one block is syomei[0]=1, the first bit value F[Sound](1) of the Fourier transformed data F[Sound](p) and the N-th bit value F[Sound](N) thereof are subjected to the information embedding process by using the above-described formulae (8), (10), (12) and (14).
The following formulae (18)xcx9c(21) represent the Fourier transformed data Fxe2x80x2[Sound](1) and Fxe2x80x2[Sound](N) obtained in the information embedding process.
Re{Fxe2x80x2[Sound](1)}=xe2x88x92Im{F[Sound](1)}xe2x80x83xe2x80x83(18)
Im{Fxe2x80x2[Sound](1)}=Re{F[Sound](1)}xe2x80x83xe2x80x83(19)
Re{Fxe2x80x2[Sound](N)}=xe2x88x92Im{F[Sound](N)}xe2x80x83xe2x80x83(20)
Im{Fxe2x80x2[Sound](N)}=Re{F[Sound](N)}xe2x80x83xe2x80x83(21)
where Re and Im indicate the real part and the imaginary part of the complex number in { }, respectively.
On the other hand, assuming that the signature data bit string to be embedded in the audio data Sound(n) corresponding to one block is syomei[1]=0, the second bit value F[Sound](2) of the Fourier transformed data F[Sound](p) and the (Nxe2x88x921)th bit value F[Sound](Nxe2x88x921) thereof are subjected to the information embedding process by using the above-described formulae (9), (11), (13) and (15).
The following formulae (22)xcx9c(25) represent the Fourier transformed data Fxe2x80x2[Sound](2) and Fxe2x80x2[Sound](Nxe2x88x921) obtained in the information embedding process.
Re{Fxe2x80x2[Sound](2)}=Re{F[Sound](2)}xe2x80x83xe2x80x83(22)
Im{Fxe2x80x2[Sound](2)}=Im{F[Sound](2)}xe2x80x83xe2x80x83(23)
Re{Fxe2x80x2[Sound](Nxe2x88x921)}=Re{F[Sound](Nxe2x88x921)}xe2x80x83xe2x80x83(24)
Im{Fxe2x80x2[Sound](Nxe2x88x921)}=Im{F[Sound](Nxe2x88x921)}xe2x80x83xe2x80x83(25)
By performing the inverse discrete Fourier transform on the data Fxe2x80x2[Sound](p) which has been obtained by subjecting the Fourier transformed data F[Sound](p) corresponding to the audio data Sound(n) in one block to the information embedding process by using the above-described formulae (8)xcx9c(15), information-embedded audio data Soundxe2x80x2(n) is obtained as represented by the following formula (26).                                           Sound            xe2x80x2                    ⁢                      xe2x80x83                    ⁢                      (            n            )                          =                              ∑                          n              =              0                        N                    ⁢                      xe2x80x83                    ⁢                                                    F                xe2x80x2                            ⁡                              [                Sound                ]                                      ⁢                          xe2x80x83                        ⁢                          (              p              )                        ⁢                          xe2x80x83                        ⁢                          ⅇ                              j                ⁢                                  xe2x80x83                                ⁢                2                ⁢                                  xe2x80x83                                ⁢                π                ⁢                                  xe2x80x83                                ⁢                pn                ⁢                                  /                                ⁢                N                                                                        (        26        )            
Next, the embedded-information extraction process will be described briefly.
In this process, the Sound(n) and the Soundxe2x80x2(n) are respectively subjected to the Fourier transform, and the respective Fourier-transformed data are compared. When the values of these data are different from each other, the signature data bit string is extracted with the signature bit data being 1. When the values of these data are identical, the signature data bit string is extracted with the signature bit data being 0.
The algorithm will be briefly described in the following.
In { }, n moves from 1 to N in order.
{
If F[Sound](n)=F[Soundxe2x80x2](n) does not hold, syomei[nxe2x88x921]=1
If F[Sound](n)=F[Soundxe2x80x2](n) holds, syomei[nxe2x88x921]=0
}
As described above, in recent years, as a method for protecting the copyright for video data or audio data, the watermarking technique for embedding information indicating the copyright holder or the like (relevant information) in these data to clarify the data source, has been put to practical use.
However, there are various watermarking methods for embedding such relevant information in digital data and, under the existing circumstances, it is difficult to handle the digital data in which the copyright information is embedded, by a reproduction apparatus or the like which employs a predetermined watermarking method.
Meanwhile, an electronic distribution system has been proposed, in which video data or audio data is distributed not through a distribution medium (data recording medium) but through a network.
In the electronic distribution system, distribution of video data has a considerable technical problem because the quantity of video data is large. However, distribution of audio data can be easily realized even in the existing limited network band because the quantity of audio data is smaller than the quantity of video data, and therefore, the audio data distribution will be carried out in the near future.
Hence, there will be a demand for a system for embedding relevant information which specifies the copyright holder or the like in audio data to be distributed, by using a watermarking method, to identify the source of the audio data.
The present invention is made to solve the above-described problems and has for its object to provide a data processing apparatus which can appropriately perform electronic distribution of audio data and, moreover, which can protect the copyright for the electronic-distributed audio data.
It is another object of the present invention to provide a data processing apparatus which can convert digital data in which information has been embedded by using various watermarking methods, to data which can be processed by a predetermined watermarking method.
It is still another object of the present invention to provide a data recording medium which contains digital data having a data structure by which appropriate electronic distribution of audio data is performed and the copyright for the electronic-distributed audio data is protected.
It is a further object of the present invention to provide a data recording medium which contains, as digital data in which information has been embedded by various watermarking methods, digital data having a data structure which can be processed by a predetermined watermarking method.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed description.
According to a first aspect of the present invention, there is provided a data processing apparatus for receiving various kinds of information-embedded digital data which correspond to different watermarking methods and have been obtained by embedding relevant information in supply digital data to be supplied from the distribution end to the user, and processing these information-embedded digital data. This apparatus comprises a data obtaining unit for obtaining a desired information-embedded digital data as input digital data; a method information obtaining unit for obtaining used method information which corresponds to the input digital data and indicates the watermarking method used for the process of embedding the relevant information; an information extraction unit for extracting the relevant information from the input digital data by using the used watermarking method, in accordance with the used method information which has been obtained; and an information embedding unit for embedding the extracted relevant information or processed information obtained by processing the relevant information, in the input digital data or in processed digital data obtained by subjecting the input digital data to a predetermined data processing, by using a predetermined watermarking method. Therefore, when extracting the relevant information, it is avoided that wrong information is extracted by using another method. Further, when removing the relevant information, it is avoided that a portion other than the embedded relevant information is undesirably changed by using another method.
As the result, at the distribution end from which digital data such as audio data is distributed to the user, the relevant information can be embedded as a watermark in the supply digital data to be supplied, by using a desired watermarking method. In other words, especially when the digital data is recorded on a recording medium at the user end, the distribution end of the digital data can select a watermarking method which provides the least degradation due to the information embedding process. Further, the distribution end can select the optimum method according to the communication rate or the like when transmitting the digital data.
Further, when the information-embedded digital data obtained from the network N is recorded on a writable recording medium, a watermarking method, which is different from the watermarking method used for embedding information in the supply digital data at the distribution end, can be used for embedding information in the digital data to be written in the recording medium. Therefore, information can be embedded in digital data by a watermarking method adapted to an apparatus which reproduces the digital data.
According to a second aspect of the present invention, in the data processing apparatus of the first aspect, the relevant information embedded in the information-embedded digital data is information relating to the copyright holder of the supply digital data. Therefore, the copyright for the supply digital data to be supplied from the distribution end to the user can be protected.
According to a third aspect of the present invention, in the data processing apparatus of the first aspect, the information embedding unit embeds the relevant information or the processed information in the input digital data by using the predetermined watermarking method, thereby generating output digital data. Therefore, regardless of the watermarking method by which the relevant information has been embedded in the obtained digital data, reproduction apparatuses as domestic electrical equipment which employ the predetermined watermarking method can appropriately reproduce the information-embedded digital data, according to the embedded information like copyright information.
According to a fourth aspect of the present invention, the data processing apparatus of the third aspect further comprises a data reproduction unit for reproducing the output digital data. Therefore, reproduction of the obtained information-embedded digital data can be controlled according to the relevant information.
According to a fifth aspect of the present invention, the data processing apparatus of the third aspect further comprises a data recording unit for recording the output digital data. Therefore, regardless of the watermarking method used for the information-embedded digital data, the information-embedded digital data can be stored, as digital data corresponding to a predetermined watermarking method, in recording media used in reproduction apparatuses as domestic electrical equipment.
According to a sixth aspect of the present invention, the data processing apparatus of the first aspect further comprises an information removal unit for removing the relevant information from the input digital data in accordance with the used method information obtained by the method information obtaining unit, thereby generating information-removed digital data as the processed digital data; and the information embedding unit embeds the relevant information or the processed information in the information-removed digital data by using the predetermined watermarking method, thereby generating output digital data. Therefore, the relevant information in the input digital data, which corresponds to various watermarking methods, can be replaced with the relevant information corresponding to the predetermined watermarking method.
According to a seventh aspect of the present invention, the data processing apparatus of the sixth aspect further comprises a data reproduction unit for reproducing the output digital data. Therefore, reproduction of the obtained information-embedded digital data can be controlled according to the relevant information. Further, when the processed digital data is digital audio data which has been obtained by removing the embedded information from the input digital data, reproduction of the information-embedded digital data can be performed according to the processed digital data, while minimizing degradation of sound quality.
According to an eighth aspect of the present invention, the data processing apparatus of the sixth aspect further comprises a data recording unit for recording the output digital data. Therefore, regardless of the watermarking method used for the obtained information-embedded digital data, the information-embedded digital data can be stored, as digital data of less noise, in recording media used in reproduction apparatuses as domestic electrical equipment which employ the predetermined watermarking method.
According to a ninth aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data comprises a first data portion of a fixed length and a second data portion of a variable length; the used method information indicating the used watermarking method is embedded in the first data portion by the used watermarking method; and the method information obtaining unit obtains the used method information indicating the used watermarking method, from the first data portion of the input digital data. Therefore, the method information obtaining unit can easily detect the position of the used method information in the information-embedded digital data.
According to a tenth aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data has a data structure including a plurality of data packets; the used method information indicating the used watermarking method is included in a header of a predetermined data packet amongst the plural data packets; and the method information obtaining unit obtains the used method information indicating the used watermarking method from the header of the predetermined data packet of the information-embedded digital data. Therefore, the method information obtaining unit can easily detect the position of the used method information in the information-embedded digital data.
According to an eleventh aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data is followed by an auxiliary data portion; the used method information indicating the used watermarking method is included in the auxiliary data portion; and the method information obtaining unit obtains the used method information indicating the used watermarking method from the auxiliary data portion which follows the information-embedded digital data. Therefore, the method information obtaining unit can easily detect the position of the used method information in the information-embedded digital data.
According to a twelfth aspect of the present invention, in the data processing apparatus of the first aspect, the data obtaining unit is able to obtain the information-embedded digital data from at least one of plural data recording media and plural data transmission paths; and the method information obtaining unit decides the used watermarking method in accordance with any of the data recording media and the data transmission paths from which the information-embedded digital data has been obtained, and obtains the used method information corresponding to the result of the decision. Therefore, it is not necessary to insert the watermarking method information in the digital data to be distributed from the distribution end to the network. Further, it is not necessary to insert the watermarking method information in the distributed digital data to be stored in the recording medium. Thereby the data processing for the supply digital data to be supplied from the distribution end to the user can be reduced.
According to a thirteenth aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data is multiplexed digital data obtained by multiplexing audio digital data, or video digital data, or audio digital data and video digital data. Therefore, the relevant information embedded in the various kinds of digital data, which corresponds to various watermarking methods, can be converted to the relevant information corresponding to the predetermined watermarking method.
According to a fourteenth aspect of the present invention, in the data processing apparatus of the first aspect, the data obtaining unit has an antenna for receiving a broadcast wave from a broadcasting station, and a received-wave decoder for demodulating the wave received by the antenna to output the information-embedded digital data. Therefore, the information-embedded digital data can be obtained from the broadcast wave from the broadcast station.
According to a fifteenth aspect of the present invention, in the data processing apparatus of the first aspect, the data obtaining unit has a data reading unit for reading the information-embedded digital data stored in a bulk memory, from the bulk memory. Therefore, the information-embedded digital data can be obtained from DVD-ROM, DVD-RAM, or a semiconductor recording media.
According to a sixteenth aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data is obtained by embedding plural pieces of relevant information in the supply digital data by using plural watermarking methods; plural pieces of used method information corresponding to the plural watermarking methods are included in the information-embedded digital data, as the used method information indicating the used watermarking method; and the information extracting unit is able to extract the relevant information corresponding to each of the plural watermarking methods from the input digital data, according to the used method information corresponding to the plural watermarking methods. Therefore, various kinds of relevant information can be embedded in the supply digital data by optimum watermarking methods.
According to a seventeenth aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data is obtained by embedding plural pieces of relevant information in the supply digital data by using plural watermarking methods; and the information embedding unit embeds a predetermined one of the plural pieces of relevant information in the input digital data by using the predetermined watermarking method, thereby generating output digital data. Therefore, a desired relevant information amongst the various kinds of relevant information embedded in the digital data can be adapted to the predetermined watermarking method.
According to an eighteenth aspect of the present invention, in the data processing apparatus of the first aspect, the information-embedded digital data is obtained by embedding plural pieces of relevant information in the supply digital data by using plural watermarking methods; and the information embedding unit embeds a predetermined number of relevant information amongst the plural pieces of relevant information, in the input digital data, by using the corresponding watermarking methods amongst the plural watermarking methods or a watermarking method different from the plural watermarking methods, thereby generating output digital data. Therefore, a desired relevant information amongst the various kinds of relevant information embedded in the digital data can be adapted to the required watermarking method.
According to a nineteenth aspect of the present invention, in the data processing apparatus of the sixth aspect, the information-embedded digital data is obtained by embedding plural pieces of relevant information in the supply digital data by using plural watermarking methods; and the information embedding unit embeds a predetermined one of the plural pieces of relevant information in the processed digital data by using the predetermined watermarking method, thereby generating output digital data. Therefore, the information-embedded digital data containing various kinds of relevant information can be converted to new digital data in which a desired one of the various kinds of relevant information is adapted to the predetermined watermarking method.
According to a twentieth aspect of the present invention, in the data processing apparatus of the sixth aspect, the information-embedded digital data is obtained by embedding plural pieces of relevant information in the supply digital data by using plural watermarking methods; and the information embedding unit embeds a predetermined number of relevant information amongst the plural pieces of relevant information, in the processed digital data, by using the corresponding watermarking methods amongst the plural watermarking methods or a watermarking method different from the plural watermarking method, thereby generating output digital data. Therefore, the information-embedded digital data containing various kinds of relevant information can be converted to new digital data in which a desired one of the various kinds of relevant information is adapted to the predetermined watermarking method.
According to a twenty-first aspect of the present invention, there is provided a data recording medium in which information-embedded digital data is recorded, which information-embedded digital data is obtained by embedding relevant information in supply digital data to be supplied from the distribution end to the user. In this recording medium, the information-embedded digital data is composed of a first data portion having a fixed length and a second data portion having a variable length; used method information indicating the watermarking method used for embedding the relevant information in the supply digital data is embedded in the first data portion; the relevant information is embedded in the second data portion by the used watermarking method indicated by the used method information; and the relevant information can be extracted or removed from the second data portion by using an appropriate watermarking method, according to the used method information. Therefore, an apparatus which obtains the information-embedded digital data can decide the watermarking method used for embedding the information in the digital data. Thereby, the apparatus can perform extraction or removal of the embedded information without extracting wrong information by using another method or changing a portion other than the embedded information by using another method. Further, the apparatus can easily detect the position of the used method information in the information-embedded digital data.
As the result, at the distribution end from which digital data such as audio data is distributed to the user, the relevant information can be embedded as a watermark in the supply digital data to be supplied, by using a desired watermarking method. In other words, especially when the digital data is recorded on a recording medium at the user end, the distribution end of the digital data can select a watermarking method which provides the least degradation due to the information embedding process. Further, the distribution end can select the optimum method according to the communication rate or the like when transmitting the digital data.
Further, when the information-embedded digital data obtained from the network N is recorded on a writable recording medium, a watermarking method, which is different from the watermarking method used for embedding information in the supply digital data at the distribution end, can be used for embedding information in the digital data to be written in the recording medium. Therefore, information can be embedded in digital data by a watermarking method adapted to an apparatus which reproduces the digital data.
According to a twenty-second aspect of the present invention, in the data recording medium of the twenty-first aspect, the used method information is embedded in the first data portion of the information-embedded digital data by a predetermined watermarking method. Therefore, the used method information indicating the used watermarking method can be easily extracted.
According to a twenty-third aspect of the present invention, in the data recording medium of the twenty-first aspect, plural pieces of used method information indicating different used watermarking methods, which have been used for embedding the relevant information in the supply digital data, are embedded in the first data portion of the information-embedded digital data. Therefore, an apparatus which obtains the information-embedded digital data can control reproduction of the digital data according to the plural pieces of used method information.
According to a twenty-fourth aspect of the present invention, there is provided a data recording medium in which information-embedded digital data and used method information are recorded. The information-embedded digital data is obtained by embedding relevant information in supply digital data to be supplied from the distribution end to the user. The used method information indicates the watermarking method used for embedding the relevant information in the supply digital data, and follows the information-embedded digital data. In this recording medium, the information-embedded digital data has a data structure in which the relevant information can be extracted or removed by using an appropriate watermarking method, according to the used method information. Therefore, an apparatus which obtains the information-embedded digital data can perform processing or reproduction of the digital data according to the used method information. Further, the apparatus can decide the watermarking method used for embedding the information in the digital data. Therefore, the apparatus can perform extraction or removal of the embedded information without extracting wrong information by using another method or changing a portion other than the embedded information by using another method.
According to a twenty-fifth aspect of the present invention, in the recording medium of the twenty-fourth aspect, plural pieces of used method information indicating different watermarking methods, which have been used for embedding the relevant information in the supply digital data, are recorded as the used method information. Therefore, an apparatus which obtains the information-embedded digital data can perform processing or reproduction of the digital data according to the used method information.